The recently released HA
sequence from A/swine/Iowa/03032/2010
has a six BP duplication which includes G158E. Thus instead of
the wild type sequence for positions 156-159 changing from KKGN to
KKEN, as found in many low reactors, the Iowa swine sequence has
KKEKEN, which almost certainly leads to significant immunological
escape.

The isolate was collected a month ago and the genetic background is
similar to humans infected by swine H1N1 in 2007 in Ohio.
However, the sequence has also acquired pH1N1 sequences that are found
in almost all pH1N1 isolates. Moreover, most of these
polymorphisms are non-synonymous and at least one polymorphism traces
back to 1918.

These acquisitions raise concerns that this virus could quickly gain
efficient and sustained transmission in humans, leading to a
co-circulating H1N1 pandemic.